Associated File:
Identifies the type and name of a file containing additional information
needed to view an SGML encoded digital object or to play a RealAudio digital object.
This attribute is repeatable and may identify a group of files such as an SGML
packet of files or an individual file such as
an SGML entity file.

Associated File Name:
Part of combination attribute Associated File. Identifies a file needed to view
an SGML encoded digital object or to play a RealAudio digital object.

RealAudio - RAM Streaming File - Contains digitized
sound that is played as it is received over a network. Progressive Networks' RealAudio
is one of the leading providers of streaming sound.
For more on streaming, click here.

SGML - Catalog File - Points to Document Type Definitions(DTD).
Contains the public IDs for the DTD and the DTD's specific location. Also contains the
public IDs for ISO Entities available for use with the DTD.
A catalog file is viewer-specific. All viewers require some form of catalog file.

SGML - Entities - Describe character sets and other data associated
with a DTD. May be unique to a specific DTD or public, that is, associated with
more than one DTD.

SGML - Entity File -
Identifies all the external links within an SGML-encoded document and
maps to the related file. The Entity File is unique to a specific
SGML-encoded document and must be present if the SGML-encoded document
contains external links which are not declared within the document itself.

SGML - Entityrc File - A software-dependent file
that is used to map the Public Identifier of a DTD with the descriptions
and actual file names of the style sheet and navigator files.
This is how, for example, Panorama knows which files to use for a given DTD.
Entityrc files are viewer-specific. All viewers require some form of
entityrc file.

SGML - Navigator - Describes which tags are to be used for
creating a navigation instrument for documents associated with a particular DTD.
A navigator is similar to a style sheet. It can be applied to more than one DTD
as long as the tags are the same. Currenlty (03/97), unique to viewer. In future,
will comply with the Document Style Semantics and Specifications Language (DSSSL)
standard. All SGML viewers use some type of navigator.

SGML - Packet - The set
of files required to view an SGML-encoded document. Currently (03/97)
some of these files are specific to the software (Panorama) used to view
the document. Any number of SGML packets may exist with different combinations
of any types of SGML associated files.

SGML - Style Sheet - Describes display rules for tags in a DTD.
The style sheet can be applied to any document using a DTD with the same tags.
Currenlty (03/97), unique to viewer. In future, will comply with the
Document Style Semantics and Specifications Language (DSSSL) standard.
All SGML viewers require a style sheet.

Bit Depth: Indicates the number of different colors or
shades of gray that can be stored in each pixel of a scanned (i.e., raster) image.
Sometimes referred to as "Color Depth."
Usually expressed as number of bits per pixel.

Currently recognized bit depths and the number of colors or gray tones
associated with them are listed below.

Bit Depth

Associated Colors / Gray Tones

1-bit

Black and white only; no shades of gray

4-bit

16 colors or gray tones

8-bit

256 color or gray tones

24-bit

16.7 million color or gray tones

32-bit

16.7 million color or gray tones and 8-bits of special effects

Color Mode: Indicates whether colors or shades of gray
are associated with the Bit Depth of a scanned (i.e., raster) image.
Currently recognized color modes are listed below:

Color Mode

Meaning

Bit Depth(s)

Bitonal

Black and white only; no shades of gray.

1-bit

Color

Color tones; no shades of gray.

4-bit 8-bit24-bit32-bit

Grayscale

Shades of gray; no color tones.

8-bit

Creation Information:
Provides information about the creation of data element content associated
with a digital object. Includes creation date, indication of any special
equipment used, and identification of the vendor or LC unit that created
the digitized content.

Creation Date:
Date that a piece of Library of Congress collection material
was processed to produce a digital object destined for the inclusion
in the Repository. Expressed in YYYYMMDD format. Date Created is
part of the combination attribute
Creation Information.

Creator:
Identifies the organization responsible for processing a piece of
collection material to produce a digital object destined for the
inclusion in the Repository. Such organizations may be either
LC work units or commercial vendors. Creator is part of the
combination attribute
Creation Information.

Data Element Content: The
actual data carried in a digital object. Example: the actual
image of a page or photograph.

Data Element Description:
Briefly identifies the nature of the content carried in a data element. If this
attribute is not present, the data element inherits the description found in its
associated digital object.

Data Element Relationship Information:
Indicates the relationship between data elements of the same digital object.
Such relationships include: ordinal ordering of sibling data elements in a
presentation sequence (e.g., 1 of 26) and whole part relationships
(e.g., grid coordinates; details).

Note that Data Element Relationship Information is repeatable as long as
the data element relationship types
to be specified do not include "Stand Alone."
Note also that while there can be more than one occurrence of
Data Element Relationship Information in a data element, no more than one
of each data element relationship type can be specified.

Data Element Relationship
Type: Part of the combination attribute
Data Element Relationship Information. Indicates the nature of
the relationship between data elements of the same digital object.
Such relationships include:

Stand-alone - Each data element
is complete in itself (e.g., an individual photograph).
This is the default Data Element Relationship Type.

Presentation sequence - Each data element is complete in itself
but also part of a larger presentation sequence (e.g., individual pages in a book).
Formed by all of a digital object's data elements.

Part of a whole
- Each data element is NOT complete in itself; the whole is made up of all
of a digital object's data elements. Examples of a part include: the upper left panel
of a billboard poster, a section of a large map, a detail from an image, and
the center panel of a panoramic photograph.

Since whole/part relationships take a variety of forms,
this relationship type is further broken down into the following subtypes:

Alpha-Numeric Grid - Relationship where
the whole is a nonmotion visual item
(e.g., raster map) and the data element's
position as part of the whole is expressed as a set of alpha-numeric coordinates.
The alphabetic coordinate indicates the vertical (column) position; the numeric
indicates the horizontal (row) position. Both coordinates are relative to the
upper left corner of the whole, which has coordinate values a:1.

Detail - A small part of an image, enlarged to show
a close-up of its features. A detail is considered part of an image but is displayable
without the rest of the image. Details are identified by a "one-up count" number preceded
by the lower case letter x (e.g., x01, x02, x03). Note that these identifying numbers are
relative to the image of which the detail is a part.

Data Element Relationship
Value: Part of the combination attribute
Data Element Relationship Information.
Provides relationship information needed to present data elements
of a digital object for printing or display. Information will
vary according to the Data Element Relationship Type specified.

Relationship Value

Relationship Type

Null

Stand-alone

Sequence number, followed by a colon and the
total number of data elements in the sequence.(example: 2:41)

Presentation Sequence

Grid coordinates; column:row (example:
a:5)

Alpha-Numeric Grid

Detail number (example: x01)

Detail

NOTE: Values for "Presentation Sequence" and "Stand Alone" can be
clearly expressed but values for "Part of Whole" cannot. This is because
the "Part of Whole" Data Element Relationship Type covers a wider
variety of conditions than originally thought. "Part of Whole" will need
additional analysis and clarification. (02/27/97)

Data Element Rights and
Permissions: Indicates, at a summary level, any
limitations on the use to which the content of a data element can
be put and the rationale for those limitations.
If this attribute is not present, the data element
inherits the rights and
persmissions indicated in its associated digital object.

Data Element Use:
Indicates how the content of a data element within a digital object
is used. Data element uses defined to date (04/97) include:

Data Element Use

Meaning

Pointer

Points to another, subordinate
digital object (e.g., handle).

Archival

Data element contains the richest, most complete
representation of the data content that is available.

Service

Data element contains data content that is
used to respond to, or service, user requests for data presentation (e.g., display, or printing).
Such data content usually is less than archival but greater than preview
in its level of completeness and quality.

Preview

Data element contains data content that is
used to provide a summary presentation of the data. Such data content usually is the smallest, shortest,
briefest representation of the data that is available. Data content that is used for preview purposes includes
thumbnail images, film clips, and sound bites.

Data Size: The
length of the content portion of a data element. Expressed in
number of bytes.

Data Size Unit:
Identifies the unit of measure used to express the length of the
content portion of a data element.

Code

Data Size Unit

KB

Kilobytes

MB

Megabytes

GB

Gigabytes

TB

Terabytes

PB

Petabytes

Data Type: Indicates the
nature of the data found in the content portion of a data element.
If applicable, Data Type is expressed as MIME type.
Examples of data types identified to date (04/97) include:

Date Data Element Last
Revised: Indicates the date upon which a
data element of a digital object was last updated or changed.
Expressed in YYYYMMDD format. Part of data element combination attribute
Last Data Element Revision.
Default is the same date as found in Date Data Element Deposited.

Date Last Revised:
Indicates the date upon which a digital object was last updated or
changed. Expressed in YYYYMMDD format. Part of combination
attribute Last Revision. Default is the
same date as found in Date Deposited.

High level metaobject: A digital object
containing metadata that is NOT subordinate to any other digital object
(i.e., has no parent digital object). Usually will have at least one
directly subordinate digital object.

Metaobject: A digital object containing
metadata that may be subordinate to one or more digital objects and superior
to others.

Hybrid digital object: A digital object that both contains
actual data content and points to one or more subordinate digital
objects.

Equipment:
Identifies any special equipment used to produce a digital
object destined for the inclusion in the Repository (e.g., scanner).
Equipment is part of the combination attribute
Creation Information.

Extent Information: Indicates the
range over which a digital object reaches as expressed in space or time.
Digital object extent types include pixel dimensions, such as for a scanned image,
and duration, such as the playing time of an audio recording or motion picture.
Extent Information is a combination attribute with two subordinate attributes,
extent type and extent value.

Extent Type: Part of the combination attribute Extent. Indicates whether the extent is a range of space
or time and the nature of how it is expressed. Extent types currently defined are listed below.

Duration - The interval of time
during which something exists or proceeds. The playing time of a digital
object such as an audio recording or motion picture.

Extent Value:
Part of the combination attribute Extent Information.
Provides measurement values used to indicate the dimensions or playing time
of a digital object. Extent Value will vary according to the Extent Type
specified. Value formats for currently defined Extent Types are
indicated below.

ExtentType

Name

Unit ofMeasure

Value Format

001

Dimensions

Pixels

WWWW:HHHH

(W = width and H = height)

002

Duration

Time

HHHH:MM:SS.SSS

(H = hours, M = minutes,and S = seconds)

Handle: A
sequence of lower case alphanumeric characters that uniquely
identifies a digital object; the persistent global identifier of a
digital object. A handle contains a Naming Authority designation,
followed by a slash (/), followed by a Unique String identifying
the individual digitized object.
Example: loc.ndlp/amrlp.3a16116.1

The Naming Authority Designation consists of a high level Naming
Authority designation (e.g., "loc") followed by a period (.)
and a Lower Level Naming Authority designation (e.g., "ndlp").
For the list of currently recognized Name Authority designations associated
with LC, click here.

The Unique String portion of the Handle consists of an aggregate name
followed by the name of a metaobject within the aggregate and then the
Local Name Convention for the individual digital object being identified.
Single periods (.) are used to separate these Unique String components.

Note that aggregate names are often found in MARC field 856, subfield d or
its equivalent. Note also that while the Unique String may be assigned
based on how the digital object was produced, it operates as a nonsemantic identifier.

The Local Name Convention for an individual digital object is
analogous to "file ID" in the current (mid-1996) naming
schema for Coolidge Compilation digital objects.

Instance:
Identifies the version of a digital object with which a data element is
associated. The data element may contain either a pointer to another digital
object or actual object data (e.g., an actual image or part of
an image). An instance may be comprised of more than one of a digital
object's data elments.

Last Data Element Revision:
Indicates the date and time that a data element of a digital object in the
Repository was last updated or changed.

Last Revision:
Indicates the date and time that a digital object in the Repository
was last updated or changed.

Number of Instances:
Indicates the number of versions of a digital object that are represented by
the data elmenets associated with that object.

Original Content Type:
Indicates the general physical nature of the original collection item from which
a portion of digitized content was produced. The purpose of the Original Content Type
attribute is to facilitate digital object presentation. Original Content Type does
not indicate how the digital object was produced (e.g., scanned, encoded),
nor does it indicate the genre or subject content of the digital object.
Original content types include:

Owner of Digital Object:
Identifies the institution or individual who owns a digital object.
The default for owner of digital objects in the repository is
"Library of Congress."

Page Information:
Provides information about a special function or characteristic of a
data element associated with scanned, non-motion visual content;
in particular, text and raster maps.

Page Type:
Part of combination attribute Page Information.
Indicates a special function or characteristic of a data element
associated with text content. Page types include:

Feature:
A distinctive function performed by the
original content from which a data element's data content was
derived. Examples: cover, table of contents, index, end paper.
For a list of currently recognized features, click
here.

Plate Number:
The number used on the original content from which a data element's
data content was derived to identify it as a particular
plate in the original work.
Plates are separately numbered; they do not form part of either the
preliminary or the main sequences of pages or leaves in the original work.

Page Number:
The page number (printed or inscribed) that actually appears on the original
content from which a
data element's data content was derived. This number is not necessarily
the same as the number of the data element in a
presentation sequence.
For example, a book may have a table of contents or introductory material
such as a prologue that is numbered using roman numerals. Thus the page
marked as page number 1 might actually be the ninth page in the sequence
of pages. Simiarly, the table of contents might start on the ninth page of
a book but bear the page number "ix."

Sheet Number:
The number used on the original content from which a data element's
data content was derived to identify it as a particular
sheet in the original work.
Sheets are separately numbered; they do not form part of either the
preliminary or the main sequences of pages or leaves in the original work.

Side:
Indicates which side of a page, sheet, or
leaf in the original work is represented by
the original content from which a data element's data content was derived.
If a side is not indicated, the front side is assumed.

Identifying Target: Target image used by the
National Digital Library Program to uniquely identify every document
to be scanned. Many contain special scanning and text conversion
instructions.

Time Data Element Last Revised:
Indicates the time of day at which a data element of a digital object was last updated
or changed. Expressed in HHMMSS.SS format. Part of data element combination
attribute Last Data Element Revision.
Default is the same time as found in Time Data Element Deposited.

Time Last Revised:
Indicates the time of day at which a digital object was last updated or changed.
Expressed in HHMMSS.SS format. Part of combination attribute
Last Revision. Default is the same
time as found in Time Deposited.